noun 1. engineering a joint in which the rounded end of one part fits into the cavity of another part ⇒ The round socket joint into the seat provides a rotational movement which helps in obtaining a correct alignment. 2. anatomy a joint in which the rounded end of one bone fits into a cavity in another bone ⇒ He held his right arm out in front of him then eased it back until it was in line with the side of his body. It's got something to do with the socket joint., ⇒ The hip is the biggest ball and socket joint in the body.
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